"If we admit that we're very class-based — which we really are — that reveals the uncomfortable truth that we're not as democratic as we like to pretend to be, which is the heart and soul of this country," he said. "If we're not truly democracy, then what are we? That's the whole justification for creating this country."
Citations Needed has a great episode about the phrase "middle-class".
"It’s a capitalist carrot hovering over our heads telling us such things are possible if we Only Work Harder. More than anything, it's a way for politicians to gesture towards populism without the messiness of mentioning––much less centering––the poor and poverty."
https://citationsneeded.libsyn.com/episode-91-its-time-to-retire-the-term-middle-class
Yeah everyone thinks they're "middle class" because in the US the poor are trained to think aspirationally and the rich are trained to downplay the exploitative source of their wealth.
I remember feeling pressure when I was a kid to say I was middle class when we had some sort of assembly where a guy came in and taught us the difference between 'needs' and 'wants'.
Somewhere in there kids were telling what class they were and I felt the need to say my family was middle class when we were nowhere near that, but I remember my dad saying we were 'middle class' at one point or another during my childhood, so I didn't know any better.
My mom used to wake my 3 sisters and I up at 4 in the morning to go pile into the backseat of the frozen ass car to drive my dad to work. This was so she had the car to then take us to school at 7:30, and she could run errands if necessary later on.
I would get made fun of at school for my shoes being so small that my big toe stuck out the front and for my coat not zipping up properly because it was too small. This in brutally cold midwestern winters.
We ate casseroles or hotdogs or soup for dinner most nights and we weren't rich enough to bring "snacks" to school for "snack time" so I was always one of a couple of kids that had a family that couldn't afford to send snacks to school, while other kids were eating their gushers and fruit roll-ups and whatever else right in my face.
But you know.. I'd be damned if I was going admit to anyone that we were poor as fuck.
It honestly depends on how you want to define it and under what framework. In Marxism the definition of class depends on the relationship to the means of production. Obviously using the Marxist framework is the most accurate to describe what's actually happening and as Marxists we should use those definitions and try to inform people as best we can that proletariat and bourgeoisie are the two main and oppositional classes (primary contradiction) in capitalism. But like Mardoniush pointed out there still are other classes since the relationship to the means of production can be more complicated than just straight ownership vs labor despite the antagonism of those two classes being the primary contradiction.
Still, none of those are a "middle class" and you are completely right about how one of the big reasons that term gets heavily used is so the parts of the proletariat that are not impoverished can feel elevated above those who are. But that right there means there is a material difference between certain subsets of the proletariat that gets called "middle class" and "lower class." There is a large subset that historically in the US was generally well off (comparatively) to the subset that lives in poverty conditions, and it is true that the former subset is shrinking while the latter subset is growing (along with the intensity of the contradictions). It is not wrong to point this out, and "middle class" is definitely not meaningless when used this way, it's just that using the word "class" to describe this phenomenon is deliberately muddying the waters and it's not using the term according to a Marxist framework. Don't mistake that to mean that what the OP article is saying is untrue or isn't happening, because it most definitely is happening! It's just bad semantics.
There are more classes (there are still a few owner-operated farms, which technically count as Yeomanry, and the PB is a different class to the HB), Proles and Bougies are just the main ones.